Spark ignition devices



May 17, 1966 H. WIEGERT SPARK IGNITION DEVICES Filed May 16, 1962 HARRY IN VEN TOR.

TTORNEY United States Patent 3,252,037 SPARK IGNITION DEVICES Harry Wiegert, Cedarburg, Wis., assignor to Controls Company of America, Schiller Park, Ill., a corporation of Delaware Filed May 16, 1962, Ser. No. 195,221 8 'Claims. (Cl. 313-141) This invention relates to ignition devices and, more particularly, to low voltage spark ignition devices.

In spark ignition devices it is desirable to achieve as hot an arc as possible which, in a-low voltage spark ignition device, gives rise to two conflicting design considerations. The temperature of an arc varies directly with its length, i.e. the longer the arc the higher is the temperature of the arc, but the greater the distance between electrodes the higher the voltage must be to cause sparkover which is inconsistent with the provision of a low voltage spark ignition device.

Considering only the voltage necessary to draw an arc, perhaps the most ideal electrode configuration is a pair of pointed electrodes. The electrical field in such a gap is concentrated at the points of the electrodes so that spark-over occurs at a relatively lower voltage than would be the case for similarly spaced electrodes of other configurations, e.g. blunt or spherical. However, pointed electrodes erode rapidly when an arc is drawn and do not maintain a fixed gap distance nor desired gap characteristics for the characteristics of the gap change as the electrodes erode and the distance therebetween increases. Blunt electrodes, although they maintain a predetermined gap space, require a relatively high er spark-over voltage as the electrical field is diffused over the electrode surfaces; further, the diffused field results in erratic operation as the break down voltage of the gap varies considerably.

An object of this invention is to provide a spark'ignition device which possesses the low voltage spark-over characteristics of one incorporating pointed electrodes while exhibiting the durability of one incorporating blunt electrodes.

Another object of this invention is to provide a spark ignition device having improved low voltage characteristics.

Still another object of this invention is to effect a re- .duction in spark-over voltage for a given spark gap.

A further object of this invention is to improve the low voltage characteristics of 'a spark ignition device by reducing the spark-over voltage thereof while maintaining consistent spark-over voltage characteristics.

For the achievement of these objects this invention contemplates the association with the electrodes of a spark ignition device of means for concentrating the electrical field between the electrodes to reduce its sparkover voltage while maintaining consistent spark-over characteristics.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the embodiments shown in the drawings, in which:

FIG. 1 is a cross sectional view of a preferred embodiment of this invention;

FIG. 2 is an end view thereof;

FIG. 3 is a diagrammatical illustration of an alternative spark gap construction;

FIG. 4 is a diagrammatical illustration of another alternative construction;

FIG. 5 is a diagrammatical illustration of still another alternative spark gap construction; and

FIG. 6 is a diagrammatical illustration of a further alternative construction.

With reference to the drawings, the ignition device 3,252,637 Patented May 17, 1966 embodying this invention includes a body 10, of suitable electrical insulating material, having an upper portion 12 and a lower portion 14. An electrical conductor 16 extends through body portions 12 and 14 and extends exteriorly of one end of the body to form an electrode 18. Conductor 16 includes a threaded portion 20 for receipt of nuts 22 and 24 which engage and hold body portions 12 and 14 in assembled relationship with conductor 16 extending therethrough.

A generally C-shaped electrical conductor 28 includes a lower leg 30 having an aperture 32 through which body portion 12 extends. the leg 30 so that upon tightening of nuts 22 .and 24 conductor 28 is securely clamped between body portions 12 and 14. Conductor 28 also includes an upper leg which terminates a predetermined distance from electrode 18 to provide an electrode 34 and a spark gap 36.

In a manner well known in the art, conductor 16 is connected to a suitable source of electrical power and electrode 34 is suitably connected to ground to establish an electrical circuit including the spark gap 36.

A member 38 is connected to electrode 34 and is posi tioned adjacent spark gap 36, in this instance in overlying relationship with the spark gap. Member 38 is made of electrically conductive material but can be dielectric material if desired. Member 38, being connected to electrode 34 will be at the electrical potential of that electrode and is spaced from the electrode 18 a distance greater than the distance between the electrodes 34 and 18 to maintain gap 36 as the main spark gap. Member 38 being in proximity to gap 36 attracts the electrical field in gap 36 so as to concentrate it at localized, oppositely disposed portions on the electrodes 34 and 18, in this instance between the upper, inner corners of the electrodes. Withthe electrical field being concentrated between localized, opposed portions on the electrodes, gap 36 will spark-over at a voltage considerably lower than that which would be required to spark-over the gap without member 38. Particularly, a 20 to 25 percent reduction in the spark-over voltage of a given gap can be achieved by positioning means such as member 38 in proximity to the gap; or, by including such means, the length of a gap can be increased without increasing the voltage required for spark-over which would give a hotter spark for the same voltage; By achieving a concentration of the electrical field between the electrodes, spark gap 36 approaches the characteristics of a gap including pointed electrodes and yet exhibits the durability of a spark gap including blunt electrodes. In eflYect, the result is a spark gap which possesses the desirable features of both a pointed electrode spark gap and a blunt electrode spark gap.

Reference will now be made to FIG. 3 for the description of an alternative spark gap arrangement. Here electrodes 40 and 42 are spaced apart a predetermined distance to establish a spark gap 44 therebetween. A dielectric member 46 is supported on electrode 42 adjacent spark gap 44 and is operative to shift the field between the electrodes 40 and 42 upwardly to concentrate the electrical field, and, in the manner already described, cause spark-over at a lower voltage.

Since member 46 is not an electrical conductor it can, if desired, be placed relative to electrode 40 at a distance less the spark gap, allowing it to be positioned nearer the spark gap to exert more of an influence on the electrical field. It should be noted that here the member for achieving concentration of the field even though it does not overlie the entire spark gap is still effective to concentrate the field.

In FIG. 4 a pair of conductors 48 and 50 are illustrated as having overlapping ends and forming electrodes 52 and 54 respectively and having a spark gap 56 therebetween.

Body portion 14 is disposed below,

The end of conductor 5% overlies spark gap 56 and is operative to concentrate the electrical field between the upper inner corner of electrode 52 and a point on electrode 56 oppositely disposed from that corner.

FIG. 5' illustrates still an additional alternative construction of this invention. Here electrodes 53 and 69 are spaced apart to form a spark gap 62 therebetween. A member 64, suitably supported so as to be electrically isolated from both electrodes, is positioned in proximity to gap 62 but physically spaced from both electrodes 58 and 6%. Since member 64 is electrically isolated it can be either an electrically conductive or an insulating member. Member 64 will shift the electrical'field upwardly on electrodes 58 and 6t and concentrate this electrical field on the upper inner corners of the electrodes to provide spark-over at a lower voltage.

In one form or another, the embodiments already discussed have positioned the means for shifting and concentrating the magnetic field in overlying relationship with the spark gap. A position below or to either side of the spark gap will give equally satisfactory results. More specifically, in PEG. 6 a pair of electrodes 66 and 68 are positioned in relative spaced relation to form a spark gap '70 therebetween. Member '72, of conductive or dielectric material as discussed above,'is mounted suitably so as to be positioned below the spark gap and will be etlective to shift and concentrate the electrical field between opposed points on the electrodes. In this instance, between the lower inner corner of the electrodes.

it should be noted that the means for shifting and concentrating the electrical field between the electrodes is positioned in proximity to the spark gap to effectuate concentration of the electrical field but does not physically bridge the spark gap. More particularly, the field concentrating means is spaced from at least one of the electrodes so as not to afford a physical connection between the electrodes.

Although this invention has been illustrated. and described in connection with particular embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made therein Without departing from the spirit of the invention or from the scope of the appended claims.

What I claim is:

1. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from said first electrode a predetermined distance to form a spark gap therebetween, and anelectrically conductive member connected to one of said electrodes and overlying said spark gap, said electrically conductive member being disposed in spaced relation from the other of said electrodes a distance greater than the gap distance and in proximity to said gap to concentrate the field in said gap and between said electrodes.

2. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from said first electrode a predetermined distance to form a spark gap therebetween, and an electrically conductive member connected to one of said electrodes, said electrically conductive member disposed in spaced relation from the other of said electrodes a distance greater than said predetermined distance and disposed in proximity to said gap to concentrate in the field in said gap and between said electrodes.

3. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from saidfirst electrode a predetermined distance to form a spark gap therebetween, an electrically conductive member, and means supporting said electrically conductive member in overlying relation with at least a portion of said spark gap and in spaced relation from at least one of said electrodes a distance greater than said predetermined distance and in proximity to said spark gap to concentrate the field in said gap and between said electrodes.

4. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from said first electrode a predetermined distance to form a spark gap therebetween, an electrically conductive member, and means supporting said electrically conductive member in spaced relation from atleast one of said electrodes a distance greater than said predetermined distance and in proximity to said spark gap to concentrate the field in said gap and between said electrodes.

5. A spark ignition device comprising, in combination,

a first electrode, a second electrode spaced from said first electrode a predetermined distance to form a spark gap therebetween, and means connected to one of said electrodes and disposed in proximity to said spark gap for concentrating the field in said gap and between said electrodes, said means being spaced from the other of 'said electrodes a distance greater than said predetermined distance.

6. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from said first electrode a predetermined distance to form'a spark gap therebetween, a field concentrating member electrically separated from at least one of said electrodes and disposed in proximity to said spark gap to concentrate the field in said gap and between said electrodes.

7. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from said first electrode a predetermined distance to form a spark gap therebetween, and a dielectric member connected to one of said electrodes and spaced from the other of said electrodes, said dielectric member disposed in proximity to said spark gap and operative to concentrate the field in said gap and between said electrodes. 7

8. A spark ignition device comprising, in combination, a first electrode, a second electrode spaced from said first electrode to form a spark gap therebetween, a dielectric member, and means supporting said dielectric member in spaced relation from at least one of said electrodes and overlying at least a portion of said'spark gapfor concentrating the field in said gap and between said electrodes.

References Cited by the Examiner UNITED STATES PATENTS 2,164,578 7/1939 Doyle 313-141 JOHN W. HUCKERT, Primary Examiner.

DAVID J. GALVIN, Examiner.

L. ZALMAN, Assistant Examiner. 

1. A SPARK IGNITION DEVICE COMPRISING, IN COMBINATION, A FIRST ELECTRODE, A SECOND ELECTRODE SPACED SAID FIRST ELECTRODE A PREDETERMINED DISTANCE TO FORM A SPARK GAP THEREBETWEEN, AND AN ELECTRICALLY CONDUCTIVE MEMBER CONNECTED TO ONE OF SAID ELECTRODES AND OVERLYING SAID SPARK GAP, SAID ELECTRICALLY CONDUCTIVE MEMBER BEING DISPOSED IN SPACED RELATION FROM THE OTHER OF SAID ELECTRODES A DISTANCE GREATER THAT THE GAP DISTANCE AND IN PROXIMITY TO SAID GAP TO CONCENTRATE THE FIELD IN SAID GAP AND BETWEEN SAID ELECTRODES. 